1. Field of the Invention
The present invention relates to an electrical machine having an electrical component including a rotor component and a stator component arranged in a housing, and having power electronics for controlling the machine arranged on the electrical component. The invention also relates to a drive arrangement for a vehicle having such an electrical machine arranged between the engine and the transmission.
2. Description of the Related Art
Electrical machines are generally rotating machines which use a magnetic field either on the motor principle to convert electrical energy into mechanical energy, or on the generator principle to convert mechanical energy into electrical energy.
Electrical machines of this type, which may, for example, be in the form of synchronous machines or asynchronous machines, have an electrical component which has a rotor component and a stator component. The stator component, also referred to as the stator, is generally the stationary part, while the rotor component, also referred to as the rotor, is the rotating part. Depending on the nature of the configuration of the electrical machine, the stator component comprises, for example, a laminated core which is formed from a yoke and a number of winding teeth. An electrical winding (coil) is arranged in the slots between these winding teeth. When a current flows through these windings, this produces the magnetic field of the electrical machine. The rotor component comprises, for example, a laminated core on which a number of magnets, for example permanent magnets, are arranged. Electrical machines of said type are in widespread use in the prior art, and are used in widely differing ways.
The electrical component of the electrical machine is normally arranged inside a housing, by which means it is protected against external influences and damage.
If, for example, the electrical machine is used in a drive arrangement for a vehicle, it may act, for example, as a so-called starter-generator. A starter-generator is, for example, a permanent-magnet synchronous machine which is arranged between the crankshaft of the internal combustion engine and a clutch, or a transmission, in the drive arrangement. The starter-generator first of all allows the internal combustion engine to be started. Furthermore, while driving, it can act as a generator, that is to say replacing the starter and the generator in the vehicle. The starter-generator can be connected via its housing to the internal combustion engine, or to the transmission.
Electrical machines such as the starter-generator described above are generally controlled via so-called power electronics. One example of such power electronics is that described in DE 199 13 450.2, which corresponds to U.S. Ser. No. 09/533,580, incorporated herein by reference. These power electronics comprise a power section which has a number of capacitors and a number of power semiconductors, with the power semiconductors and capacitors being connected to a power busbar system. Furthermore, the power electronics have a control unit for the power section. A high-performance microcontroller, for example, is provided as the controller. A power supply device is also provided. The power electronics are used to control the electrical component or components connected to them.
Particularly if the electrical machine is intended to be used in a vehicle, there is generally only a very small amount of space available, so that the physical dimensions of the electrical machine need to be optimized.
In the past, it has been normal practice in the vehicle industry to install the power electronics separately from the electrical component in the vehicle. In this case, the power electronics were normally mounted fixed to the vehicle. The disadvantage of this solution was, firstly, that it required a large amount of physical space. Furthermore, appropriate wiring was required for the power connections and sensor connections between the power electronics and the electrical component. The use of relatively long cables for this wiring resulted in a range of losses. If the electrical machine was configured as a starter-generator, these losses were, for example, losses in the generator mode, voltage drops during cold starting of the vehicle, problems relating to electromagnetic compatibility (EMC) and the like.
There was thus a need to avoid these disadvantages. One step to solving the problem was, for example, to arrange the previously separate power electronics for controlling the electrical machine on the electrical component, or to integrate the power electronics in that component.
One such solution is described in U.S. Pat. No. 5,678,646. This document discloses a drive arrangement for a vehicle, in particular a road vehicle. The prior-art description in this document cites a solution in which an electric motor and its electronic controller (power electronics for the motor) are integrated in a single housing. The housing in this case comprises two half-housings which can be connected to one another, with the components of the electric motor being arranged predominantly in one half-housing, and the components of the controller being arranged predominantly in the other half-housing. These two half-housings are then joined together.
This solution variant was found to have a disadvantage in that there was only ever one completed system whose individual components could not be modified for different vehicle types.
In order to avoid these disadvantages, U.S. Pat. No. 5,678,646 now describes a solution in which the electrical machine is modular. The electrical component of the electrical machine is located in one module, while the power semiconductors, and possibly parts of the control device, are accommodated in at least one further module. The individual modules are arranged axially one behind the other, and are attached to one another.
Modern power electronics, such as the electronics described in DE 199 13 450 2 cited above, have a wide range of components, some of which are quite large. Furthermore, the use of power busbar systems which, for example, are in the form of busbars, very largely dispenses with the need to connect the individual components by means of cables. One example of this is described in more detail further below within the description of the invention.
When such power electronics are used, an axial arrangement would, on the one hand, occupy a relatively large amount of physical space. Furthermore, the use of busbars makes it necessary for the individual components of the power electronics to be accommodated as close as possible to those components of the electrical component which need to be connected to them.
Against the background of the cited prior art, the present invention is based on the object of providing an improved electrical machine and an improved drive arrangement for a vehicle, in which the power electronics can be arranged on the electrical component of the electrical machine in a simple and cost-effective manner while avoiding the disadvantages cited in the prior art and while at the same time occupying only a small amount of space.
According to the first aspect of the invention, an electrical machine is provided having an electrical component which has a rotor component and a stator component and is arranged inside a housing, and having power electronics for controlling the electrical machine, which are arranged on the electrical component. According to the invention, the housing has a first housing wall which surrounds the electrical component in the circumferential direction, and has an accommodation space which extends radially outward from the first housing wall with respect to the rotation axis of the rotor component, and the individual components of the power electronics are arranged inside the accommodation space.
This configuration of the electrical machine results in a very compact and space-saving shape, with the individual components of the power electronics being arranged in the immediate vicinity of the electrical component.
The fundamental idea of the present invention is for the power electronics to be accommodated in a specific manner in the housing of the electrical component. In this case, this results in a radial arrangement of the power electronics, rather than an axial arrangement, with respect to the electrical component. This means that the component with the power electronics is accommodated in a housing which surrounds the electrical component in the electrical machine in the circumferential direction.
To this end, the invention first of all provides for the housing to have a first housing wall which surrounds the electrical component in the circumferential direction. The first housing wall has a first surface, which faces the electrical component. Furthermore, the first housing wall has a surface which faces away from the electrical component. This surface forms a first boundary wall for an accommodation space in the housing, with the accommodation space pointing radially outward from the first housing wall with respect to the rotation axis of the rotor component. The individual components of the power electronics are accommodated in this accommodation space, which is specified in even more detail in the rest of the following description.
This results in a number of advantages. Firstly, the first housing wall, which is located between the individual components of the power electronics and the electrical component, means that the individual components are physically separated from one another. This is important, for example, for cooling since, in particular, individual components of the power electronics, such as power semiconductors and the like, have to be cooled particularly well to allow them to produce their full performance. Examples relating to this will be explained in more detail further below.
Although it is possible to arrange the individual components of the electrical machine in a particularly compact and space-saving manner, a certain amount of modularity can nevertheless be ensured, since individual components of the power electronics can be matched to different conditions. Specifically, the configuration of the electrical machine according to the invention makes it possible for the individual components of the power electronics to be replaced even after assembly of the electrical machine. This is particularly advantageous for servicing and repair purposes, as well.
Furthermore, the electrical machine according to the invention requires only a small amount of physical space, even when relatively large components are used for the power electronics. The physical space can be enlarged only in the radial direction, but not in the axial direction. This is advantageous in particular when using the electrical machine according to the invention in the vehicle sector. If, for example, the electrical machine is arranged in a drive arrangement of a vehicle between the engine and a transmission, there is generally spare physical space in the radial direction of the electrical machine as a result of the geometrical configuration of the engine and of the transmission which flank the electrical machine, and which space is generally unused. This can now be made use of by the electrical machine according to the invention. The electrical machine according to the invention allows the physical space requirement to be reduced further in comparison to the drive arrangement which is known from the prior art and is described in U.S. Pat. No. 5,678,646.
Normally, electrical machines, and/or their electrical components, have a substantially circular configuration. Depending on the type of electrical machine, the rotor component rotates either inside or outside the stator component. In this case, the two components are arranged spaced apart radially with respect to the rotation axis of the rotor component. The electrical component produced in this way is surrounded by the first housing wall in the circumferential direction. The circumference of the electrical component is in this case formed by itsxe2x80x94circularxe2x80x94outer boundary. The first housing wall, which is formed in the circumferential direction of the electrical component, thus has a surface which has the length of a line forming the outer boundary of the electrical component and running back from a starting point to the output point.
The width of the first housing wall is governed by the requirement and the application. Examples relating to this will be described in more detail in the rest of the description below.
As has already been mentioned, the configuration of the electrical machine according to the invention makes it possible for the distances between the individual components of the power electronics and the components of the electrical component to be further minimized. This makes it possible to achieve a higher efficiency for the electrical machine, a smaller voltage drop, in particular during starting of the electrical machine, improved electromagnetic compatibility (EMC) and the like. The arrangement according to the invention avoids the previously required power cables between the electrical component and power electronics, as well as the corresponding connections. The electrical machine can be fit in a simple manner, with less use of materials at the same time.
The invention is not limited to specific electrical machines. In fact, it can be used for all possible types of electrical machines. In this context, one may quote, for example, internal-rotor or external-rotor electrical machines, synchronous machines, asynchronous machines, permanent-magnet machines and the like. In one advantageous refinement, the electrical machine may be in the form of a starter-generator, in particular for a vehicle.
The invention can be used advantageously for electrical machines having high motor currents of more than 300 A peak.
The electrical machine can be completely prefabricated.
The power electronics may have components which are described, for example, in DE 199 13 450.2, cited initially, so that the disclosure content and description in that document also relate to the present invention.
The housing may advantageously have a second housing wall which extends radially outward at an angle, preferably at right angles, from the first housing wall in order to bound the accommodation area. The individual housing walls are used firstly for attachment of individual power electronics components. Furthermore, if the materials are chosen appropriately, they can be used to dissipate the heat losses produced in the power electronics components. The invention is not limited to specific embodiments relating to how the two housing walls can be connected to one another or aligned with respect to one another.
In a further refinement, the accommodation area can be bounded by at least one cover element on its side opposite the first housing wall and/or on its side opposite the second housing wall. The cover element or elements can advantageously be arranged to be detachable. In this way, the individual power electronics components can be mounted very easily in the accommodation area of the housing. The accommodation area can then be sealed by the cover element or elements on the sides which are still exposed. The installed power electronics are thus covered, so that they are protected against external influences, such as the ingress of water or dirt, and against damage.
The cover element or elements can advantageously be configured such that it or they seal or seals the contours of a component (for example an internal combustion engine) on which the housing of the electrical machine is mounted, so that no particles whatsoever can enter the accommodation area of the housing via this joint either.
One or more cooling openings can advantageously be provided in the first and/or second housing wall. Additional cooling can be produced via these cooling openings, by means of an air flow driven by the rotor component. The individual cooling openings preferably have suitable devices to prevent dirt particles or the like from being able to enter the power electronics. Such devices may be, for example, seals, for example labyrinth seals, filters or the like.
Furthermore, one or more cooling channels can be provided in the first and/or second housing wall. A suitable cooling medium can flow through these cooling channels to allow heat losses which are produced to be dissipated reliably and as completely as possible. In particular, the cooling medium flowing through the cooling channels can be used to dissipate those heat losses which are produced in the power electronics components connected to the housing walls. For this purpose, the cooling channels are arranged in particular in those areas of the housing walls in which the corresponding power electronics components are also mounted.
In a further refinement, one or more openings and/or recesses can be provided in the first and/or second housing wall and/or in at least one cover element.
The openings, or recesses, firstly have the task of making it easier to fit and adjust individual power electronics components in the accommodation area. For example, it is thus possible to retighten screw connections, via which individual power electronics components are connected to one another, by inserting appropriate tools through the openings or recesses, without having to open the housing.
The openings/recesses also offer the capability, however, for various sensors to be connected to the electrical component, or external components to be connected to the power electronics. For example, it is important to know the temperature of the rotor component. Appropriate rotor temperature sensors are provided for this purpose. If the electrical machine is an external-rotor machine, the rotor temperature can be sensed without making contact using optical methods (infrared sensors) or the like, for example. If the electrical machine is an internal-rotor machine, with the stator component being located outside the rotor component, appropriate temperature sensors can be connected to the stator windings. The temperatures measured on the stator windings make it possible to deduce the rotor temperature. The values recorded by the individual sensors are transported via the openings/recesses which are provided to the power electronics, where they are processed further.
Further openings/recesses can be provided to identify the rotation speed and/or rotation angle of the rotor component. Sensors such as this are generally referred to as rotor position sensors.
The openings/recesses may, of course, also carry out other functions, for example being used to produce connections between individual power electronics components and individual components of the electrical components.
The power electronics may advantageously have one or more capacitors which is or are arranged on the first and/or second housing wall. In this case, the capacitors can be arranged at any desired points on the first and/or second housing wall, depending on the number of them and the application. The capacitors can be connected to the housing wall via a suitable connection, for example a screw connection. This means that the capacitors rest directly on the housing wall, thus forming a contact surface between the capacitor and the housing wall, via which, for example, heat losses produced in the capacitors can be dissipated.
Furthermore, the power electronics may have one or more power semiconductors which is or are arranged on the first and/or second housing wall. Once again, heat losses produced in the power semiconductors can be emitted to the housing wall, and dissipated via it, via the direct contact surface between the power semiconductor and the housing wall.
All types of power semiconductors are possible. Suitable power semiconductors are, preferably, MOSFETs, IGBTs or the like. The power semiconductors are chosen on the basis of the power requirements for the power electronics.
The configuration of the power electronics is very heavily dependent on the voltage level required. For this reason, the number of capacitors and power semiconductors can vary depending on the design of the power electronics, so that the invention is not limited to a specific number of capacitors and power semiconductors.
The power semiconductors can preferably be arranged via a clamping connection on the first and/or second housing wall. Such a connection can, firstly, be implemented very easily, with a very good clamping effect being produced at the same time. If the power semiconductors are pressed via such a clamping connection onto the housing wall, this connection results in only a low thermal resistance.
In one advantageous refinement, the power semiconductors can be arranged on the first housing wall, with the first housing wall being made planar in this area. The first housing wall normally has a contour which follows the curved shape of the electrical component, so that the individual power semiconductors have to be mounted on this curved housing wall. In order to simplify the attachment of the power semiconductors and in order at the same time to produce a contact surface which is as large and flat as possible between the power semiconductors and the housing wall, the housing wall is made planar in those areas in which the power semiconductors are mounted on it.
An analogous situation likewise applies to the arrangement of the capacitors or of other components of the power electronics on the first housing wall.
The power electronics can advantageously have a power busbar systemxe2x80x94also referred to as a busbar. Individual components of the power electronics, for example the capacitors and power semiconductors, are connected to the power busbar system, and are interconnected via it. The connection can be produced via suitable screw connections. The power semiconductors can advantageously be connected to the power busbar system via connecting legs provided on them, for example via a suitable connecting lug or the like. The power busbar system is preferably composed of copper.
Furthermore, the power busbar system can advantageously be connected to one or more connecting contacts for the stator component. The connecting contacts can in turn be connected to a corresponding interconnection arrangement for the windings of the stator component. In order to split the current better, the interconnection arrangement can be connected to the power busbar system at a number of points. The power busbar system can be connected to the connecting contacts via, for example, a suitable screw connection, plug-in connection or the like.
The interconnection arrangement for the stator windings of the stator component may be in the form of annular conductors. This avoids any need for individual interconnection of the respective stator coils to the connecting contacts and thus to the power busbar system. Connecting conductors which are electrically insulated from one another are used instead, are configured as ring conductors and are arranged interleaved radially inward with respectively different diameters. The individual coil ends are connected to the connecting conductors at the respective points provided for this purpose. This drastically reduces the number of connecting contacts which are required and need to be connected to the power busbar system.
The power electronics may advantageously have a drive device for the power semiconductor or semiconductors. This drive device, which is, for example, in the form of a drive board or the like, is preferably used for supplying signals to the power semiconductors. In this case, the control connections of the semiconductors, for example the gate of a field-effect transistor, make contact with the drive device. The drive device may in turn have a number of openings and/or recesses through which the connecting legs of the power semiconductors can be passed in order to be connected to the power busbar system. In this way, the drive device can be mounted in a particularly space-saving manner between the power busbar system and the power semiconductors.
Furthermore, the power electronics may have a control device. The control device, which may be a control board, is preferably designed using SMD technology and carries all the control, monitoring and regulation functions for the power electronics, including driving the power semiconductors. A high-performance microcontroller is preferably provided to carry out the control functions in the control device, with all the functions preferably being predetermined via a CAN bus. Furthermore, the control device preferably has a device for the electrical power supply. In addition, at least one connecting element can be provided, which is advantageously a signal plug connector or the like. Depending on the requirements and the application, the control device may have further elements.
The control device is preferably connected to the drive device. In one particularly advantageous refinement, the control device and the drive device can be in the form of a single component.
The power busbar system and/or the drive device may preferably be in the form of a busbar. As a rule, busbars are used to connect electrical components to one another and to supply them with the necessary electrical power.
The power busbar system and/or the drive device may advantageously have a current measurement device. This current measurement device, which is also referred to as a current sensor, may either be in the form of an integral component (for example when the power busbar system and/or the drive device are in the form of a busbar), or may be a separate component.
The power electronics are used to drive the electrical component of the electrical machine. High currents therefore flow through the power electronics while it is operating, and these need to be measured in order to control and monitor the electrical machine. Current measurement devices generally comprise a sensor and an evaluation device connected to it.
One particularly advantageous option for current measurement is described DE 199 14 894, which corresponds to U.S. Ser. No. 09/538,653, now U.S. Pat. No. 6,380,728, incorporated herein by reference. The busbar described in that document has at least one subarea with a formed-out region. This subarea may have a special configuration and may have one or more slots in order to subdivide the current-carrying paths. This allows the current-carrying paths to be interrupted within the busbar, allowing the current flowing through the busbar to be diverted in a desired direction. A sensor for a current measurement device is advantageously provided in the vicinity of the subarea used for current measurement. This sensor, which may be designed, for example, for measuring an electrical and/or magnetic field in the busbar, is in turn connected to an evaluation device. The sensor and/or the evaluation device may advantageously, but not necessarily, be provided in the control device for the power electronics which, in this case, is preferably provided underneath the respective busbar. DE 199 14 894 describes not only a current sensor but also a particularly advantageous busbar.
The housing may advantageously have at least one cable connection for electrical connection of the power electronics to external components. Such external components may, for example, be in the form of a vehicle on-board electrical power supply system, and they will be explained in more detail in conjunction with the second aspect of the invention.
The housing may likewise have at least one cooling connection for connection to a cooling device. This cooling connection is used to control the flow of a cooling medium to and away from the electrical machine, in particular by means of the cooling channels described further above.
A fixing device can preferably be provided for at least temporarily fixing the housing on the electrical component. Such a fixing device is particularly worthwhile when the electrical component of the electrical machine is not included within any housing which entirely surrounds the electrical machine. If, for example, the electrical machine is arranged between a vehicle engine and a transmission or the like, all that is necessary is for the housing of the electrical machine to shield this in the radial direction, since, in cases such as this, the housing is normally connected, for example screwed, to the engine and to the transmission or the like. In order to allow the electrical machine to be completely prefabricated, an appropriate fixing device must therefore be provided by means of which the housing is attached to the electrical component until the installation in the drive arrangement has been completed. The invention is not limited to specific fixing devices. For example, fixing can be achieved using suitable fixing plates and fixing screws.
The width of the housing is advantageously matched to the width of the electrical machine. This width is substantially governed by the width of the electrical component, that is to say the width of the rotor component and the stator component, as well as the accessories required for them. If, for example, the electrical machine is used as a starter-generator for a vehicle, situations can occur in which the coupling or clutch required for such a vehicle, or at least parts of it, is or are likewise arranged in the region of the electrical component. This means that a unit such as this comprising an electrical machine and coupling or clutch has a somewhat greater width than would be the case with an electrical machine without a coupling or clutch. In this situation, the width of the housing must be adapted in an appropriate manner.
The housing may advantageously be in the form of a connecting flange. In this case, the connecting flange is a xe2x80x9chousing elementxe2x80x9d which shields the electrical machine in the radial direction. The connecting flange is connected via suitable connecting means, for example screws or the like, to further components, for example to an engine and to a transmission in a drive arrangement for a vehicle. The end faces of the electrical machine are then covered via corresponding end faces of the further components, for example the end face of the engine and the end face of a transmission or the like.
According to a second aspect of the invention, a drive arrangement is provided for a vehicle, in particular for a road vehicle, having an engine and a transmission connected downstream from the engine, with an electrical machine according to the invention, as described above, provided between the engine and the transmission.
The drive arrangement according to the invention makes it possible for the electrical machine to be integrated in the drive arrangement for the vehicle while occupying as little space as possible.
The housing of the electrical machine may advantageously be in the form of a connecting flange, which is connected on one side to the engine and on the other side to the transmission. This allows the electrical machine (that is to say the electrical component with the power electronics and, possiblyxe2x80x94as indicated abovexe2x80x94a coupling or clutch) to be completely preassembled and to be fit as a unit during vehicle manufacture.
It is particularly advantageous for the electrical machine to be in the form of a starter-generator. This is an electrical machine which is used not only for starting and stopping the engine but which can also carry out various functions during engine operation, for example braking functions, booster functions, battery management, active vibration damping, synchronization of the engine or the like.
The power electronics of the electrical machine can advantageously be connected to the vehicle on-board electrical power supply system. In this case, the invention is not limited to specific on-board power supply systems. For example, it is thus possible for the power electronics to be connected to a 14-volt on-board electrical power supply system, to a 28-volt on-board power supply system, or to a 42-volt on-board power supply system such as that which is now being introduced. The 42-volt on-board power supply system is an on-board power supply system which is being introduced for the first time by the automobile industry and which is intended to be used in the future for operating newly introduced additional electrical components, such as for windshield heating, electrical valve operation and the like.
The electrical machine can preferably be connected to a cooling device for the vehicle, in particular to a cooling circuit for the engine. In this case, the source for the cooling medium flowing through the cooling channels may be the conventional cooling circuit of the engine, for example of the internal combustion engine. The cooling connection of the electrical machine is in this case connected to the cooling circuit of the engine, so that the cooling water circulating in the engine also flows through the cooling device for the electrical machine. This means there is no need for any additional coolers, pumps or the like for the electrical component and power electronics of the electrical machine, and this has particular advantages in terms of the costs and the space requirement for the power electronics and the electrical component.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.